DE69232997T2 - Device for supplying a breathing gas and at least one anesthetic - Google Patents

Description

The invention relates to an arrangement to feed a breathing gas and at least one anesthetic.

The invention relates to an arrangement to feed a breathing gas and at least one anesthetic to a living being according to the generic term of claim 1.

An arrangement of this kind is in in US-A-3,794,027. The arrangement, an anesthetic machine for animals, contains a container, to the over a gasifier unit is connected to a gas source. An inhalation line supplies breathing gas a patient and an exhalation line conducts the breathing gas over one common Y connection from Patient away. A second carburetor unit is with the inhalation line connected. The two carburetor units can be used separately or together can be used and contain the same or different anesthetics. The contains the first carburetor unit a valve that draws the gas from the gas source through the carburetor unit through or past the carburetor unit. If that Gas is passed through the carburetor unit, it is through the liquid anesthetic pearl and evaporate it. The gas containing the anesthetic then becomes the container directed and from there to the patient. The second carburetor unit contains two cavities, the above two holes are interconnected. The first cavity forms part the inhalation line. An essentially triangular leaf can be placed in two layers, one layer only allowing that Gas passes through the first cavity. If the sheet in his is brought to another location, the gas. in the second cavity headed and passed through a wick that divided the second cavity into two halves divides. The wick is partially located in the liquid anesthetic and the gas passing through the wick vaporizes the liquid anesthetic that is released from the Wick has been absorbed. Gas containing the anesthetic flows then out through the second hole into the inhalation line.

The control of the evaporation of anesthetic is done manually in both carburettor units by activating the corresponding one Switching system (valve and blade for a certain time, if the evaporation is to take place. The concentration of the anesthetic depends mainly on two factors: the gas flow through the carburetor unit, which the Amount of anesthetic determined that is evaporated in each unit of time and the total time, while the gas is passed through the carburetor unit, the total amount of the vaporized anesthetic and will also determine the concentration. That leads to one Variation in concentration during the Time in the anesthetic fed to a patient becomes. To prevent concentrations that are too high or too low, should be an empirically established scheme for turning the Carburetor unit to be followed. With this system, by licking loss of anesthetic from the system or the like unconsidered calmly.

Another known arrangement is described in US-A-4,770,168, contains a chamber with liquid anesthetic and a positive displacement pump. About one Valve gas can be piped into the chamber in it with anesthetic saturated becomes. The gas flow from the chamber back into the line is stopped by controlled the pump. By controlling the motor that drives the pump via a the total flow in the line or the anesthetic concentration depending on the line Feedback system can reduce the concentration of the anesthetic with higher Maintain accuracy than the arrangement described above become. The chamber can also contain a thermistor. Dar motor can then also depend on the temperature in the anesthesia chamber to be controlled.

However, the pump limits the applicable one Area of using anesthetic saturated gas flow in the line. This causes problems when an overall flow is initially low is, as in the case when small children or small animals are anesthetized should be. Similar Problems arise when the overall flow is high initially. Furthermore can the required concentration level depending on the one used Anesthetic and vary from the individual patient.

Yet another known arrangement is described in EP-A-166 305. The arrangement contains one Carburettor unit in the liquid anesthetic fed to a carburetor is going to be vaporized. A breathing gas flows through the carburetor and leads the evaporated anesthetic a breathing circuit to which a patient can be connected. The Concentration of the anesthetic is controlled by periodically with a predetermined frequency and period liquid anesthetic is fed to the carburetor, i.e. similar to control those described above in connection with US-A-3,794,027 Arrangement.

An object of the invention is an arrangement according to the preamble of claim 1, in which the concentration of the anesthetic with extremely high accuracy over maintaining a wide range of total breathing gas flow.

This task is accomplished by the arrangement according to the preamble of claim 1 which in the characterizing part of claim 1 Features specified.

By arranging the first sensor behind the carburetor unit, advantageously as close to the living being as possible, returning the the current concentration of the corresponding signal and controlling the evaporation of the anesthetic with the help of a control device, a safe and advantageous control of the concentration of the anesthetic is achieved. Even a small deviation from a preselected concentration level results in an increase or decrease in the evaporation in the evaporator unit.

There are essentially three systems the for the Administration of anesthetics can be used on a patient. First there is the non-rebreathing system, in which all fed to the patient Gases can be evacuated from the system after expiration. Then there is the semi-rebreathing system where the anesthetic is used continuously circulated back to the patient, while all other gases are evacuated. Finally, there is the rebreathing system, at which all gases with the exception of carbon dioxide continuously to the patient recirculated become.

The arrangement according to the invention can in all three systems are used.

For the arrangement there are two different, advantageous types of Evaporator units. In the first type of evaporator unit causes a Throttle valve puts pressure on the liquid anesthetic, the one amount of liquid causes it to mix with the breathing gas, causing it to vaporize is, and a connecting hose carries the breathing gas with the vaporized Anesthetic to the inlet tube. The pressure difference across the Throttle valve is only one of those with a constant breathing gas flow Position of the throttle valve depends. The evaporation of the liquid Anesthetic hangs only on the pressure difference. A precise adjustment of the location of the Throttle valve, controlled by the control device, is therefore the chosen one Maintain concentration level.

A second type of evaporator unit is obtained in that the evaporator unit has a filter, the liquid Anesthetic is supplied whereby the liquid Anesthetic is evaporated by the breathing gas flowing through the filter. deviant from the second evaporator unit according to the description of the state the technology in which the liquid Anesthetic was absorbed by a wick and through that flowing the wick Breath gas has been evaporated, it is the third type of evaporator unit possible, only the required amount of liquid anesthetic to the filter supply. This results in a very precise regulation of the anesthetic concentration level. Even if the breathing gas flowing through the filter of an error in the arrangement would increase evaporated amount of anesthetic remain constant. If larger amounts of liquid Anesthetics are fed to the filter, it should be warmed because the heat of vaporization is taken from the filter itself.

According to preferred embodiments There are a number of advantageous improvements to the invention the arrangement, some of which are described below.

The arrangement can be improved by that the carburetor unit has a thermal control device, which controls the temperature in the carburettor unit and on one selected level holds. There the degree of saturation depends on the temperature, can maintain the concentration with even greater accuracy when the temperature in the carburetor unit is at a constant Temperature is maintained.

Alternatively, this can be achieved be that the carburetor unit has a thermistor for measuring the Temperature in the carburetor unit that the thermistor is connected to the control device and that the control device the flow of breathing gas through the carburetor unit depending varies from the measured temperature.

To for the first type of evaporator unit Increasing accuracy further will only be part of the total Breath gas flow passed through the evaporator unit during the Rest of the breathing gas directly from the inlet part to the inlet hose is directed.

With one in the inlet hose arranged flow sensor for measuring the total flow of breathing gas including the vaporized anesthetic, the control system can be given a wide parameter to increase accuracy. The flow sensor also creates the possibility of the total breathing gas flow to control more precisely because the contribution of the vaporized anesthetic to the river can be compensated. To achieve this, the Arrangement of a control unit that depends on the measured flow controls the input part so that the difference between the Living being fed River and the selected one Flow is minimized.

When an anesthetized patient is woken up should or if there is an unexpected increase in anesthetic concentration despite all precautions it occurs is an advantage to have a fresh gas hose close to that Connect living things with the inlet hose, through which fresh gas hose a breathing gas or an additional gas can be supplied to the living being, without first having to pass the entrance part. The supply through the fresh gas hose is controlled by the control device so that the predetermined one Overall flow is maintained. When the flow from the entrance part across a river the fresh gas hose is replaced, the concentration of the anesthetic quickly reduced to 0%.

The security of a preferred arrangement is increased in that a control signal from the control device is superimposed on a basic signal corresponding to the preselected concentration of the anesthetic agent, as a result of which the superimposed control signal increases the accuracy of the rule valve increased. Even if an error occurred in one or more sensors or the control device malfunctioned or stopped working, the basic signal would still ensure the maintenance of a concentration of the anesthetic which is harmless for the patient connected to the arrangement. It is an advantage to use a microprocessor as a control device.

To the consumption of liquid anesthetics to reduce it is an advantage to have a filter for absorption and desorption of the anesthetic. The filter is preferably in arranged the inlet hose. Such a filter, also as Known reflector, is described in WO88 / 07876 and exists made of a material that absorbs the anesthetic during expiration and while desorbs the anesthetic for inspiration. If it is together with an evaporation filter is used, the two filters can be used as a filter unit can be formed.

An alarm function for concentration of the anesthetic is created in that a second sensor for measuring the Concentration of the anesthetic arranged in the breathing gas in the inhalation line near the first sensor is and that a monitoring unit triggers an alarm if the concentration of the anesthetic outside of the predetermined interval around the preselected value. The Completely separate alarm function increases security for living beings.

In conjunction with three figures three embodiments an arrangement according to the invention described, wherein

1 Figure 2 shows a schematic block diagram of a first embodiment using a semi-rebreathing system.

2 FIG. 2 shows a schematic block diagram of a second embodiment with a rebreathing system and

3 Figure 3 shows a schematic block diagram of a third embodiment with a non-rebreathing system.

Each of the following embodiments shows only aspects of the arrangement claimed in claim 1. However relates the claimed protection applies to all aspects of the arrangement according to claim 1. All aspects of the arrangement will be according to all claims clear and obvious throughout the description.

3 shows a non-rebreathing system arrangement 4 for administering a breathing gas and an anesthetic to a patient. In the non-rebreathing system, neither the breathing gas nor the anesthetic is circulated back to the patient after use, as is the case in a rebreathing or semi-rebreathing system, each of which is in connection with the below 1 and 2 be described, the case is.

An entrance part 31 conducts gas, for example oxygen and nitrogen oxide, via a first oxygen line 301 and a nitrogen oxide line 302 to a mixing unit 32 , In the mixing unit 32 the gases are mixed before entering an inhalation line 303 are directed to the lungs 33 of a patient. A second oxygen line 304 connects the input part 31 with a carburetor unit 34 , The oxygen flow to the carburetor unit 34 is by a control valve in the input part 31 controlled. In the carburetor unit 34 liquid anesthetic is evaporated by the oxygen flow and the oxygen is saturated with anesthetic. Via a connecting line 305 the saturated oxygen becomes the inhalation line 303 passed and mixed with the main flow of breathing gas before it passed through the patient line 306 in the lungs 33 of the patient. The patient line 306 is common to the inspiration line 303 and the exhalation line 307 , Via the exhalation line 307 exhaled gas is returned to the input section 31 directed. The exhaled gas then becomes an absorber 35 conducted in which anesthetic is absorbed before the breathing gas is evacuated.

An anesthetic sensor, not shown, is after the evaporator unit 34 , preferably as close as possible to the patient's lung 33 arranged to measure the anesthetic concentration. The anesthetic sensor is with a control device 36 connected.

Any line 301 . 302 . 304 has a control valve (not shown) and all control valves are controlled by the control device 36 controlled. The control device 36 is with the input part 31 via a control line 308 and a signal line 309 connected. Via the signal line 309 becomes the control device 36 supplied with all the information necessary to control the flow in each line with the greatest possible accuracy, for example reference values for the flow, the position of each control valve, etc

The carburetor unit 34 contains a thermal control device 37 that have a well-defined temperature in the carburetor unit 34 maintains.

There are several ways to saturate the carburetor unit 34 flowing oxygen with anesthetic. One way is to let the oxygen bubble through the liquid anesthetic, another is to pass the oxygen through a wick soaked in liquid anesthetic, and a third is to pass the oxygen over the surface of the liquid anesthetic while continuously saturated oxygen exchange with unsaturated, which will be saturated by evaporation of the liquid anesthetic. Since the saturation point is constant at constant temperatures, there is high accuracy for the concentration of the anesthetic in the entire breathing gas flow by precisely controlling the flow through the carburetor unit 34 achieved. Using a feedback system results in extremely precise control.

The carburetor unit 34 can be used as an alternative to the thermal control device 37 one with the control device 36 connected thermistor 38 have, wherein the oxygen flow to the carburetor unit 36 is varied depending on fluctuations in temperature or anesthetic concentration.

The order 4 can also be provided with an anesthetic sensor as an additional safety measure. If the concentration of the anesthetic should rise or fall too low for any reason, an alarm is triggered.

In 1 describes a semi-rebreathing system arrangement, ie the exhaled gas is not circulated back to the patient, but is directed away from the patient except for the anesthetic that is circulated back.

An entrance part 10 supplied via a nitrogen oxide line 101 and the first oxygen line 102 a mixing unit 11 with oxygen and nitrogen oxide. In the mixing unit 11 the two gases are mixed to form a breathing gas that, during inspiration, flows to the lungs 12 of a patient via an inhalation line 104 is fed. From the lungs 12 the breathing gas is exhaled 105 and the input part 10 evacuated. If the patient is to be anesthetized, a carburetor unit 13 connected to the system. In the carburetor unit 13 is liquid anesthetic, e.g. B. halothane, isoflurane or enflurane. By oxygen through the carburetor unit 13 is directed, the liquid anesthetic is evaporated and the oxygen is saturated with it. The carburetor unit 13 is via a second oxygen line 103 oxygenated. The figure shows that the second oxygen line 103 around the mixing unit 11 is passed around so that the oxygen is not mixed with the other gases. From the carburetor unit 13 the oxygen and the vaporized anesthetic are passed through a connecting line 106 to a patient line 107 headed together for the inspiration line 104 and the exhalation line 105 and in which the gas flow from the mixing unit 11 and the gas flow from the carburetor unit 13 be mixed.

Since anesthetics are expensive and also must not get into the operating room, where they could influence a surgeon, the arrangement is 1 with a filter 14 in the patient line 107 provided that absorbs the anesthetic in the exhaled gas during expiration and resorbs the anesthetic in the breathing gas during inspiration. Such a filter 14 , also known as a reflector, which is used in the following as a designation, is described in WO88 / 07876.

An anesthetic sensor 15 , a flow sensor 16 and a second anesthetic sensor 17 are in the patient line 107 arranged. The three sensors 15 . 16 . 17 are each via an anesthetic signal line 108 , a flow signal line 109 and an alarm signal line 110 with a control device 18 connected. The control device 18 is via a control line 111 and a first reference value line 112 , through which a set value for the respiratory gas flow is transmitted, with the input part 10 and via a second reference value line 113 , through which a set value for the concentration of the anesthetic is transferred. The second reference line 113 also connects the entrance part 10 with the carburetor unit 13 ,

If a patient is to be anesthetized, a selected gas flow (liter / minute) and a selected ratio between oxygen and nitrogen oxide in the input part 10 set and a selected concentration level of the anesthetic is in the gasifier unit 13 set. The set values are sent via a first reference value line 112 and a second reference line 113 to a microprocessor in the control unit 18 transferred. The set concentration level of the anesthetic is also via the second reference value line 113 to the control device in the input part 10 transferred.

The control device of the input part 10 controls the valves that line the nitrogen oxide 101 and the two oxygen lines 102 . 103 supply with gas. As a result, the control device controls the valves in such a way that the set respiratory gas flow is obtained with the selected mixture of oxygen and nitrogen oxide. The valve that controls the flow through the second oxygen line is set to allow oxygen flow through the carburetor unit 13 which correlates to the selected concentration level of the anesthetic. Since no anesthetic has been absorbed by the reflector at this point in time, that is to say at the beginning of the anesthesia, a relatively large oxygen flow becomes to the gasification unit 13 guided to build the level of concentration. Via the anesthetic sensor 15 and the flow sensor 16 receives the microprocessor of the control device 18 current values of the concentration level and the respiratory gas flow. A control signal is determined by comparing these values with the reference values and via the control line 111 to the entrance part 10 transferred. The determined control signal is superimposed on the control signal from the control device. A very precise control of the set values is achieved at the same time that the arrangement 1 relatively unresponsive to errors in the anesthetic sensor 15 or the microprocessor.

To compensate for the extra flow caused by the vaporized anesthetic, the Reduced nitrogen oxide flow to maintain the selected total breathing gas flow. The reason why nitrogen oxide flow is reduced rather than oxygen flow is, of course, that it is more important to maintain the chosen oxygen concentration. As an additional security measure, the arrangement includes 1 a second anesthetic sensor described above 17 , Via the alarm signal line 110 current values of the concentration level of the anesthetic become the control device 18 transfer. The control device 18 has an alarm unit that is completely separate from the microprocessor and has the function of monitoring the concentration level. If the level falls outside a predetermined range, either lower or higher than the selected level, an alarm is activated.

The device can also be equipped with a thermal control device 37 or a thermistor 38 be equipped to increase accuracy.

2 shows a rebreathing system device in which the exhaled gas of carbon dioxide in a carbon dioxide filter 20 that in the inlet hose 201 is arranged, is cleaned. The inlet hose 201 forms one half of a cycle 200 in a patient unit 2 the device. The inspiration and expiration are indicated by a ventilation control unit indicated by dashed lines 3 controlled. At the beginning of anesthesia, the ventilation control unit 3 serves as an input part and supplies the patient unit 2 with breathing gas. Since the breathing gas is brought back into circulation, it is only necessary to add additional gas to compensate for losses and to maintain the selected gas mixture and the concentration level of the anesthetic. The second half of the cycle 200 is through an outlet hose 202 educated. As in the previous example is a patient hose 203 together for the inlet and outlet hoses 201 . 202 , The direction of flow of the breathing gas in the circuit 200 the inlet hose is to be controlled 201 and the outlet hose 202 each with a one-way valve 21 . 22 Mistake.

An evaporation filter 23 is in the inlet hose 201 , through which the breathing gas flows, arranged, whereby the liquid anesthetic that comes from the evaporator unit 24 via the evaporation hose 204 into the evaporator filter 23 is sprayed, evaporated. An anesthetic sensor 25 and a flow sensor 26 are each via an anesthetic signal line 210 and a flow signal line 211 to a control device 27 connected. The control device 27 can with the ventilation control unit 3 via a two-way communication line 205 , with the evaporator unit 24 via a first control line 206 and with a fresh gas unit 28 via a second control line 27 communicate. The evaporator unit 24 is with the control device 27 via a reference value line 208 connected.

The fresh gas unit 28 is with the inlet hose 201 via a fresh gas hose 209 connected and allows fresh gas, e.g. B. oxygen, the inlet hose 201 to lower the level of anesthetic in the breathing gas. If a patient is to be woken up from anesthesia, it is advantageous to quickly lower the anesthetic concentration. This is done by using the ventilation control unit 3 scored to get out of circulation 200 Remove breathing gas that contains anesthetic while the vaporizer unit 24 is switched off and the fresh gas circuit 200 fills with fresh gas. The fresh gas unit 28 can also supply oxygen to compensate for the patient's uptake of oxygen. To increase the accuracy of maintaining the oxygen level is an oxygen sensor 29 in the inlet hose 201 arranged. Via an oxygen signal line 212 is the oxygen sensor 29 with the control device 27 connected.

During operation, the patient unit 2 first by the ventilation control unit 3 filled with the selected breathing gas mixture. Then the ventilation control unit controls 3 inspiration and expiration. The one-way valve blocks during inspiration 22 the flow such that the breathing gas passes through the carbon dioxide filter 20 and the evaporator filter 23 into the inlet hose 201 is forced. As in the previous example, it is necessary to vaporize a large amount of anesthetic at the start of anesthesia, which in this case requires a relatively large amount of liquid anesthetic to be passed through the vaporizer tube 204 into the evaporator filter 23 is injected. To avoid the temperature due to the heat of vaporization from the filter 23 itself is avoided, the filter 23 warmed during evaporation. In the control device 27 become the via the reference value line 208 transmitted reference value and the anesthetic signal line 210 transferred current value of the concentration level of the anesthetic compared. The supply of a liquid anesthetic is then through the control device 27 controlled depending on the reference value and the current value. In the same way, the oxygen content of the breathing gas is compared by comparing one over the communication line 205 to the control device transmitted reference value with a by the oxygen sensor 29 measured, current value and supplying a sufficient amount of oxygen into the inlet hose 201 controlled. The breathing gas with its anesthetic content then passes through the one-way valve 21 into the patient tube 203 and down into the lungs 30 of the patient.

The one-way valve prevents during expiration 21 the breathing gas at it through the inlet hose to pass. The breathing gas is therefore through the one-way valve 22 out into the outlet hose 202 towards the ventilation control unit 3 directed. When an expiration is complete, the flow of inspiration is reversed and the cycle begins again.

Claims (12)

Contraption ( 1 ; 2 ; 4 ) for supplying a breathing gas and at least one anesthetic to a living being ( 12 ; 30 ; 33 ) with an evaporator unit ( 13 ; 23 . 24 ; 34 ), which contains a liquid anesthetic, whereby a predetermined concentration of the anesthetic in the breathing gas by vaporizing a defined amount of liquid anesthetic in by the vaporizer unit ( 13 ; 23 . 24 ; 34 ) breathing gas is achieved, an input part ( 10 ; 3 ; 31 ), via which the breathing gas or the gases forming the breathing gas of the device ( 1 ; 2 ; 4 ) is / are supplied, an inlet hose ( 107 ; 203 ; 306 ) which brings the breathing gas and the vaporized anesthetic to the living being ( 12 ; 30 ; 33 ) conducts, and one between the evaporator unit ( 13 ; 23 . 24 ; 34 ) and the living being ( 12 ; 30 ; 33 ) arranged first sensor ( 15 ; 25 ) for measuring the concentration of the anesthetic in the breathing gas, the first sensor ( 15 ; 25 ) with a control device ( 18 ; 27 ; 36 ), characterized in that the evaporator unit ( 13 ) has a throttle valve which exerts a pressure on the liquid anesthetic, which causes a quantity of liquid to mix with a breathing gas, causing it to evaporate, or that the vaporizer unit ( 23 . 24 ) a filter ( 23 ) to which liquid anesthetic is supplied, whereby the liquid passes through the filter ( 23 ) flowing breathing gas is evaporated, the control device ( 18 ; 27 ; 36 ) depending on the measured concentration and the predetermined concentration, the evaporation in the evaporator unit ( 13 ; 23 . 24 ; 34 ) so that the amount of liquid anesthetic evaporated minimizes the difference between the predetermined and the measured concentration of the anesthetic in the breathing gas. Device according to claim 1, characterized in that the evaporator unit ( 13 ; 34 ) a thermal control device ( 38 ) which shows the temperature in the evaporator unit ( 13 ; 34 ) controls and keeps them at a selected level. Device according to claim 1, characterized in that the evaporator unit ( 13 ; 34 ) a thermistor ( 38 ) for measuring the temperature in the evaporator unit ( 13 ; 34 ) shows that the thermistor ( 38 ) with the control device ( 18 ; 36 ) is connected and that the control device ( 18 ; 36 ) controls the evaporation depending on the measured temperature. Device according to one of the preceding claims, characterized in that only a part of the total breathing gas through the evaporator unit ( 13 ; 34 ) and that a connecting hose ( 106 ; 305 the breathing gas containing vaporized anesthetic to the main flow of breathing gas in the inlet tube ( 107 ; 306 ) leads. Device according to one of the preceding claims, characterized in that the filter ( 23 ) in the inlet hose ( 107 ) is arranged and that the control device controls the supply of liquid anesthetic to the filter so that only a required amount of anesthetic is supplied to the filter. Device according to one of the preceding claims, characterized in that a filter ( 14 ) for the absorption and desorption of the anesthetic in the inlet tube ( 107 ) is arranged. Device according to one of the preceding claims, characterized in that a flow sensor ( 16 . 26 ) in the inlet hose ( 107 . 201 ) is arranged to measure the sum of the breathing gas and the vaporized anesthetic, and that the control device ( 18 . 27 ) also controls the evaporation depending on the measured flow. Apparatus according to claim 7, characterized in that the Control unit pending of the measured flow controls the input part so that the difference between what is brought to the living being River and the selected one Value of the flow is minimized. Device according to one of the preceding claims, characterized in that a fresh gas hose ( 209 ) with the inlet hose ( 201 ) is connected in the vicinity of the living being, through which fresh gas hose ( 209 ) a breathing gas or any additional gas can be supplied to the living being without passing through the input part ( 3 ) to go through. Device according to one of the preceding claims, characterized in that a control signal from the control device ( 18 ; 27 ; 36 ) a base signal, which corresponds to the preselected concentration of the anesthetic, is superimposed. Device according to one of the preceding claims, characterized characterized in that the control device is a microprocessor. Device according to one of the preceding claims, characterized in that a second sensor ( 17 ) to measure the concentration of anesthetic in the breathing gas in the inlet tube ( 107 ) near the first sensor ( 15 ) is arranged and that a monitoring unit triggers an alarm if the anesthetic agent concentration falls outside of a predetermined interval around the preselected value.